Doppler Spread Estimation and Data Detection by Discrete Fourier Transform and Least-Square Algorithm in Time Domain for Mobile OFDM Systems

A new channel estimation and demodulation algorithm based on discrete Fourier transform (DFT) and least-square (LS) algorithm in time domain for mobile OFDM systems is proposed. From the view that the Doppler spread is a band-limited signal, the band-limited DFT is employed to represent the Doppler Spread channel with discrete serial expansion coefficients. In this way, the resulting channel coefficients are estimated by LS algorithm. Through mathematical derivation, it is proved that the data symbols can be detected by LS algorithm in time domain, which is accurate and simple. To reduce computation complexity, some simplified methods are developed. Computer simulations show that the proposed algorithm in this letter outperforms the other Doppler spread estimation and LS demodulation methods.